A light-emitting diode (LED) is a kind of semiconductor device that converts electricity into infrared rays or light using the properties of a compound semiconductor to transmit or receive a signal or that is used as a light source.
Group III-V nitride semiconductors have attracted attention as a core material of a light-emitting device, such as a light-emitting diode (LED) or a laser diode (LD), thanks to the physical and chemical properties thereof.
The light-emitting diode exhibits excellent environmentally friendly characteristics, since the light-emitting diode does not include environmentally toxic materials, such as mercury (Hg), which is used in conventional lighting fixtures, such as an incandescent lamp and a fluorescent lamp. In addition, the light-emitting diode has advantages of a long lifespan and low power consumption. For these reasons, the light-emitting diode has replaced conventional light sources.
The adhesive strengths of the respective layers within the light-emitting device package including the light-emitting device are weak, thereby deteriorating the reliability of the light-emitting device package. In addition, there is a problem that a layer having a low CTE is broken due to a difference in the coefficients of thermal expansion (CTEs) of respective layers in the light-emitting device package, thereby further lowering the reliability.